The invention relates generally to electro-mechanical operating devices such as manually-operated disconnect/grounding switches connected to machines. A particular example is in modularized feeder circuit control panels including electrical contactor circuits for power distribution centers employed in underground mining activities. Such feeder circuit control panels include a contactor as well as a manually-operated disconnect/grounding switch, the operation of which can be visually observed for safety purposes. However, embodiments of the invention are not limited to that environment or context.
Carlson U.S. Pat. No. 7,277,294 titled “Contactor Draw Out Tray,” the entire disclosure of which is hereby expressly incorporated by reference, discloses electrical circuit protector apparatus which has a stationary frame and a movable frame. The stationary frame is housed within a power distribution center and has input terminals for incoming electrical power, and output terminals for delivering electrical power to equipment operating on a feeder circuit, for example equipment in the form of a mining machine including an electric motor. The movable frame is drawer-like and includes a slide-out support tray having a front panel, and may be referred to as a draw out tray. The movable frame or draw out tray carries what may broadly be described as electrical components for the electrical circuit protector, including a disconnect/grounding switch, a contactor and a controller. A particular example of electrical components for the electrical circuit protector is a motor starter. The controller, by way of example, includes logic circuitry, communication circuitry for remote control, and protective relays. The disconnect/grounding switch is part of a mechanism which mechanically locks the movable frame relative to the stationary frame, and in particular ensures that the disconnect switch is open and the output conductors are grounded before the movable frame is drawn out of the stationary frame.
In the apparatus disclosed in Carlson U.S. Pat. No. 7,277,294, a viewing window is provided in the front panel for observing operation of the disconnect/grounding switch. Thus, Carlson U.S. Pat. No. 7,277,294 discloses an example of prior art apparatus which includes a contactor as well as a manually operated disconnect/grounding switch, the operation of which can be visually observed.